The present study examined how experts differ from nonexperts in estimation and evaluation during a judgment-and-decision task. In the experiment, the performance of 125 chess players (21 women and 104 men) whose mean age was 32.5 yr. (SD = 13.3) was examined to assess decision processes with an emphasis on postdecision differentiation and consolidation. Chess players of differing skill made evaluations of a complex middle-game chess position. The experimental condition was made by the means of chess articles with enclosed information, either about the current chess position or about other similar positions. Both novices and experts upgraded their chosen alternative in a postdecision phase more than intermediate level chess players did. Various explanations of these results are discussed.